I have a similar issue here, but not involving MobileMe.
I
've been struggling to see any of my iPhone 4 (running iOS 5 beta4) contacts appear in Lion's Address Book. It's all empty, whatever I do through iTunes (10.5 beta 4) (either manual syncing of Contacts, or by using iCloud).
At least all my contacts are still on the iPhone... but i'm stuck with a beautiful new Address Book on Lion which has 0 contacts... (or just that "Apple Inc" and "Me" contact cards)..
Without some sort of mailing list software, I'm not sure you'll really get the functionality you want.
As a workaround I would try setting up a custom tag, using an existing unused field, or something in Notes, and then creating a Smart Ground around that.
For example, all the contacts you want in your group, put 'mailing list' into their notes. Then create a SmartGroup to show those contacts.
Send the contacts to your friend, and they can import and merge the data. If they setup the same smart group, you should have the same contacts, with the same info, in that group.
The other option would be to stop her importing anything, and just use a Shared Addressbook, and maintain everything there. Google, Exchange, LDAP etc will let you use a remote address book, that isn't automatically synced to your local address book, but all contacts are accessibly, so you can both use that. In the groups page of the address book you'll see your local contacts, and remote contacts as distinct lists. Then, you'll just know to send to everyone in that shared address book.
Best Answer
I was attempting to work out a bug with iTunes. iTunes was refusing to put my contacts on my new iPod. And no groups were showing in iTunes.
One thing led to another, and I found myself looking at a blank address book. You can imagine my consternation when my iPhone contacts got smoked before I could shut down a sync.
I could import from my backups, but, like the original poster, the contacts would appear for about a second before disappearing again.
Shutting down the contacts iCloud sync and then logging out of iCloud worked. I was then able to import either one of my two backups without issue.